Citation

Tysoe A, Moore IS, Ranson C, McCaig S, Williams S. J. Sci. Med. Sport 2020; ePub(ePub): ePub.

Affiliation

Department for Health, University of Bath, UK. Electronic address: S.Williams@bath.ac.uk.

Copyright

(Copyright © 2020, Sports Medicine Australia, Publisher Elsevier Publishing)

DOI

10.1016/j.jsams.2020.01.004

PMID

31982300

Abstract

OBJECTIVES: Methodological concerns relating to acute-to-chronic workload ratios (ACWR) have been raised. This study aimed to assess the relationship between an alternative predictor variable named 'differential load', representing the smoothed week-to-week rate change in load, and injury risk in first class county cricket (FCCC) fast bowlers.

DESIGN: Prospective cohort study.

METHODS: Bowling loads and injuries were recorded for 49 professional male fast bowlers from six FCCC teams. A range of differential loads and ACWRs were calculated and subjected to a variable selection procedure.

RESULTS: Exponentially-weighted 7-day differential load, 9:21-day ACWR, 42-day chronic load, and 9-day acute load were the best-fitting predictor variables in their respective categories. From these, a generalized linear mixed-effects model combining 7-day differential load, 42-day chronic load, and 9-day acute load provided the best model fit. A two-standard deviation (2SD) increase in 7-day differential load (22 overs) was associated with a substantial increase in injury risk (risk ratio [RR]=2.47, 90% CI: 1.27-4.80, most likely harmful), and a 2SD increase in 42-day chronic load (17.5 overs/week) was associated with a most likely harmful increase in injury risk (RR=6.77, 90% CI: 2.15-21.33). For 9-day acute load, very low values (≤1 over/week) were associated with a most likely higher risk of injury versus moderate (17.5 overs/week; RR: 15.50, 90% CI: 6.19-38.79) and very high 9-day acute loads (45.5 overs/week; RR: 133.33, 90% CI: 25.26-703.81).

CONCLUSIONS: Differential loads may be used to identify potentially harmful spikes in load, whilst mitigating methodological issues associated with ACWRs.

Copyright © 2020 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Language: en

Keywords

ACWR; External load; Risk factor